Very rudimentary track editor... and headache spaghetti

.gitignore

@@ -0,0 +1,2 @@
+bundle.js
+dist/

canvas/canvas.ts

@@ -1,18 +0,0 @@
-
-type ClickEvent = {
-  mouseX: number;
-  mouseY: number;
-}
-type ClickEventHandler = (e: ClickEvent) => void;
-
-export class Canvas {
-  clickables: ClickEventHandler[] = [];
-  
-  constructor();
-  constructor(width: number, height: number);
-  constructor(width?: number, height?: number) {
-    const canvas = document.createElement('canvas');
-    canvas.width = width || 400;
-    canvas.height = height || 400;
-  }
-}

deno.json

@@ -10,9 +10,9 @@
     ]
   },
   "tasks": {
-    "dev": "deno run -RWEN --allow-run --unstable dev.ts dev"
+    "dev": "deno run -RWEN --allow-run dev.ts dev"
   },
   "imports": {
-    "doodler": "https://git.cyborggrizzly.com/emma/doodler/raw/tag/0.1.1/mod.ts"
+    "@bearmetal/doodler": "jsr:@bearmetal/doodler@^0.0.3"
   }
-}
+}

deno.lock

@@ -1,21 +1,30 @@
 {
   "version": "4",
   "specifiers": {
+    "jsr:@bearmetal/doodler@^0.0.3": "0.0.3",
     "jsr:@luca/esbuild-deno-loader@*": "0.11.0",
+    "jsr:@luca/esbuild-deno-loader@0.11.1": "0.11.1",
+    "jsr:@std/assert@*": "1.0.10",
+    "jsr:@std/assert@^1.0.10": "1.0.10",
     "jsr:@std/bytes@^1.0.2": "1.0.2",
     "jsr:@std/cli@^1.0.8": "1.0.9",
     "jsr:@std/encoding@^1.0.5": "1.0.6",
     "jsr:@std/fmt@^1.0.3": "1.0.3",
     "jsr:@std/html@^1.0.3": "1.0.3",
     "jsr:@std/http@*": "1.0.12",
+    "jsr:@std/internal@^1.0.5": "1.0.5",
     "jsr:@std/media-types@^1.1.0": "1.1.0",
     "jsr:@std/net@^1.0.4": "1.0.4",
     "jsr:@std/path@^1.0.6": "1.0.8",
     "jsr:@std/path@^1.0.8": "1.0.8",
     "jsr:@std/streams@^1.0.8": "1.0.8",
+    "jsr:@std/testing@*": "1.0.8",
     "npm:esbuild@*": "0.24.2"
   },
   "jsr": {
+    "@bearmetal/doodler@0.0.3": {
+      "integrity": "42c04b672f4a6bc7ebd45ad936197a2e32856364b66a9a9fe2b81a4aa45c7a08"
+    },
     "@luca/esbuild-deno-loader@0.11.0": {
       "integrity": "c05a989aa7c4ee6992a27be5f15cfc5be12834cab7ff84cabb47313737c51a2c",
       "dependencies": [
@@ -24,6 +33,20 @@
         "jsr:@std/path@^1.0.6"
       ]
     },
+    "@luca/esbuild-deno-loader@0.11.1": {
+      "integrity": "dc020d16d75b591f679f6b9288b10f38bdb4f24345edb2f5732affa1d9885267",
+      "dependencies": [
+        "jsr:@std/bytes",
+        "jsr:@std/encoding",
+        "jsr:@std/path@^1.0.6"
+      ]
+    },
+    "@std/assert@1.0.10": {
+      "integrity": "59b5cbac5bd55459a19045d95cc7c2ff787b4f8527c0dd195078ff6f9481fbb3",
+      "dependencies": [
+        "jsr:@std/internal"
+      ]
+    },
     "@std/bytes@1.0.2": {
       "integrity": "fbdee322bbd8c599a6af186a1603b3355e59a5fb1baa139f8f4c3c9a1b3e3d57"
     },
@@ -52,6 +75,9 @@
         "jsr:@std/streams"
       ]
     },
+    "@std/internal@1.0.5": {
+      "integrity": "54a546004f769c1ac9e025abd15a76b6671ddc9687e2313b67376125650dc7ba"
+    },
     "@std/media-types@1.1.0": {
       "integrity": "c9d093f0c05c3512932b330e3cc1fe1d627b301db33a4c2c2185c02471d6eaa4"
     },
@@ -63,6 +89,13 @@
     },
     "@std/streams@1.0.8": {
       "integrity": "b41332d93d2cf6a82fe4ac2153b930adf1a859392931e2a19d9fabfb6f154fb3"
+    },
+    "@std/testing@1.0.8": {
+      "integrity": "ceef535808fb7568e91b0f8263599bd29b1c5603ffb0377227f00a8ca9fe42a2",
+      "dependencies": [
+        "jsr:@std/assert@^1.0.10",
+        "jsr:@std/internal"
+      ]
     }
   },
   "npm": {
@@ -193,5 +226,10 @@
     "https://git.cyborggrizzly.com/emma/doodler/raw/tag/0.1.1/timing/EaseInOut.ts": "9eba3d8f5bf5e03220c93916cff6f0bbc24ecdf7550f21fd99e3aaf310f625b0",
     "https://git.cyborggrizzly.com/emma/doodler/raw/tag/0.1.1/timing/Map.ts": "3948648f8bdf8f1ecea83120c41211f5543c7933dbe3e49b367285a98ed50a9a",
     "https://git.cyborggrizzly.com/emma/doodler/raw/tag/0.1.1/zoomableCanvas.ts": "395f80ddaef83e2b37a2884d7fffefae80c2bcecb72269405f53899d5dfc9956"
+  },
+  "workspace": {
+    "dependencies": [
+      "jsr:@bearmetal/doodler@^0.0.3"
+    ]
   }
 }

dev.ts

@@ -1,19 +1,31 @@
 /// <reference lib="deno.ns" />
 
 import * as esbuild from "npm:esbuild";
-import { denoPlugins } from "jsr:@luca/esbuild-deno-loader";
+import { denoPlugins } from "jsr:@luca/esbuild-deno-loader@0.11.1";
 import { serveDir } from "jsr:@std/http";
 
+async function* crawl(dir: string): AsyncIterable<string> {
+  for await (const file of Deno.readDir(dir)) {
+    const fullPath = dir + "/" + file.name;
+
+    if (file.isDirectory) {
+      yield* crawl(fullPath);
+    } else {
+      yield fullPath;
+    }
+  }
+}
+
 async function dev() {
   const paths = [];
-  const ignoredFiles = ["bundler", "bundle", "dev"];
+  const ignoredFiles = ["bundler", "bundle", "dev", "test"];
 
-  for (const path of Deno.readDirSync("./")) {
+  for await (const path of crawl("./")) {
     if (
-      path.name.endsWith(".ts") &&
+      path.endsWith(".ts") &&
-      !ignoredFiles.find((file) => path.name.includes(file))
+      !ignoredFiles.find((file) => path.includes(file))
     ) {
-      paths.push(path.name);
+      paths.push(path);
     }
   }
   await build();

drawing/circle.ts

@@ -1,16 +0,0 @@
-import { Constants } from "../math/constants.ts";
-import { Vector } from "doodler";
-
-const circle = (ctx: CanvasRenderingContext2D, center: Vector, radius: number) => {
-  ctx.beginPath();
-  ctx.arc(center.x, center.y, radius, 0, Constants.TWO_PI);
-}
-
-export const drawCircle = (ctx: CanvasRenderingContext2D, center: Vector, radius: number) => {
-  circle(ctx, center, radius);
-  ctx.stroke();
-}
-export const fillCircle = (ctx: CanvasRenderingContext2D, center: Vector, radius: number) => {
-  circle(ctx, center, radius);
-  ctx.fill();
-}

drawing/index.ts

@@ -1 +0,0 @@
-export { drawCircle, fillCircle } from './circle.ts'

drawing/line.ts

@@ -1,6 +0,0 @@
-export const drawLine = (ctx: CanvasRenderingContext2D, x1:number, y1:number, x2:number, y2: number) => {
-  ctx.beginPath();
-  ctx.moveTo(x1,y1);
-  ctx.lineTo(x2,y2);
-  ctx.stroke();
-}

index.html

@@ -14,6 +14,18 @@
       height: 100%;
       width: 100%;
     }
+    #context {
+      position: absolute;
+      top: 0;
+      left: 0;
+      background-color: rgba(0, 0, 0, 0.5);
+      color: white;
+      padding: 10px;
+      display: flex;
+      gap: 10px;
+      max-height: 50vh;
+      overflow-y: auto;
+    }
   </style>
 </head>
 <body>

inputs.ts

@@ -0,0 +1,12 @@
+import { getContextItem } from "./lib/context.ts";
+import { InputManager } from "./lib/input.ts";
+import { StateMachine } from "./state/machine.ts";
+import { States } from "./state/states/index.ts";
+
+export function bootstrapInputs() {
+  const inputManager = getContextItem<InputManager>("inputManager");
+  inputManager.onKey("e", () => {
+    const state = getContextItem<StateMachine<States>>("state");
+    state.transitionTo(States.EDIT_TRACK);
+  });
+}

lib/context.ts

@@ -3,6 +3,8 @@ type ContextStore = Record<string, any>;
 const contextStack: ContextStore[] = [];
 const defaultContext: ContextStore = {};
 
+const debug = JSON.parse(localStorage.getItem("debug") || "false");
+
 export function setDefaultContext(context: ContextStore) {
   Object.assign(defaultContext, context);
 }
@@ -23,12 +25,63 @@ export const ctx = new Proxy(
       for (let i = contextStack.length - 1; i >= 0; i--) {
         if (prop in contextStack[i]) return contextStack[i][prop];
       }
-      if (prop in defaultContext) return defaultContext[prop]; // ✅ Fallback to default
+      if (prop in defaultContext) return defaultContext[prop];
       throw new Error(`Context variable '${prop}' is not defined.`);
     },
   },
-) as Record<string, any>;
+) as Record<string, unknown>;
 
 export function getContext() {
   return ctx;
 }
+export function getContextItem<T>(prop: string): T {
+  return ctx[prop] as T;
+}
+export function setContextItem<T>(prop: string, value: T) {
+  Object.assign(contextStack[contextStack.length - 1] ?? defaultContext, {
+    [prop]: value,
+  });
+}
+
+if (debug) {
+  setInterval(() => {
+    let ctxEl = document.getElementById("context");
+    if (!ctxEl) {
+      ctxEl = document.createElement("div");
+      ctxEl.id = "context";
+      document.body.append(ctxEl);
+    }
+    ctxEl.innerHTML = "";
+    const div = document.createElement("div");
+    const pre = document.createElement("pre");
+    const h3 = document.createElement("h3");
+    h3.textContent = "Default";
+    div.append(h3);
+    pre.textContent = safeStringify(defaultContext);
+    div.append(pre);
+    ctxEl.append(div);
+    for (const [idx, ctx] of contextStack.entries()) {
+      const div = document.createElement("div");
+      const pre = document.createElement("pre");
+      const h3 = document.createElement("h3");
+      h3.textContent = "CTX " + idx;
+      div.append(h3);
+      pre.textContent = safeStringify(ctx);
+      div.append(pre);
+      ctxEl.append(div);
+    }
+  }, 1000);
+}
+
+function safeStringify(obj: any) {
+  const seen = new WeakSet();
+  return JSON.stringify(obj, (key, value) => {
+    if (typeof value === "object" && value !== null) {
+      if (seen.has(value)) {
+        return "[Circular]"; // Replace circular references
+      }
+      seen.add(value);
+    }
+    return value;
+  }, 2);
+}

lib/input.ts

@@ -1,17 +1,26 @@
+import { Vector, ZoomableDoodler } from "@bearmetal/doodler";
+import { getContextItem } from "./context.ts";
+
 export class InputManager {
   private keyStates: Map<string | number, boolean> = new Map();
   private mouseStates: Map<string | number, boolean> = new Map();
   private mouseLocation: { x: number; y: number } = { x: 0, y: 0 };
   private mouseDelta: { x: number; y: number } = { x: 0, y: 0 };
+
+  private keyEvents: Map<string | number, () => void> = new Map();
+  private mouseEvents: Map<string | number, () => void> = new Map();
+
   constructor() {
     document.addEventListener("keydown", (e) => {
       this.keyStates.set(e.key, true);
+      this.keyEvents.get(e.key)?.call(e);
     });
     document.addEventListener("keyup", (e) => {
       this.keyStates.set(e.key, false);
     });
     document.addEventListener("mousedown", (e) => {
       this.mouseStates.set(e.button, true);
+      this.mouseEvents.get(e.button)?.call(e);
     });
     document.addEventListener("mouseup", (e) => {
       this.mouseStates.set(e.button, false);
@@ -33,9 +42,42 @@ export class InputManager {
     return this.mouseStates.get(key);
   }
   getMouseLocation() {
+    if (getContextItem("doodler") instanceof ZoomableDoodler) {
+      return getContextItem<ZoomableDoodler>("doodler").screenToWorld(
+        this.mouseLocation.x,
+        this.mouseLocation.y,
+      );
+    }
     return this.mouseLocation;
   }
+  getMouseLocationV() {
+    if (getContextItem("doodler") instanceof ZoomableDoodler) {
+      return new Vector(
+        getContextItem<ZoomableDoodler>("doodler").screenToWorld(
+          this.mouseLocation.x,
+          this.mouseLocation.y,
+        ),
+      );
+    }
+    return new Vector(this.mouseLocation);
+  }
   getMouseDelta() {
     return this.mouseDelta;
   }
+
+  onKey(key: string | number, cb: () => void) {
+    this.keyEvents.set(key, cb);
+  }
+  onMouse(key: string | number, cb: () => void) {
+    this.mouseEvents.set(key, cb);
+  }
+
+  offKey(key: string | number) {
+    const events = this.keyEvents.get(key);
+    this.keyEvents.delete(key);
+    return events;
+  }
+  offMouse(key: string | number) {
+    this.mouseEvents.delete(key);
+  }
 }

lib/resources.ts

@@ -0,0 +1,38 @@
+export class ResourceManager {
+  private resources: Map<string, unknown> = new Map();
+  private statuses: Map<string, Promise<boolean>> = new Map();
+
+  get<T>(name: string): T {
+    if (!this.resources.has(name)) {
+      throw new Error(`Resource ${name} not found`);
+    }
+    return this.resources.get(name) as T;
+  }
+
+  set(name: string, value: unknown) {
+    if (typeof (value as EventSource).addEventListener === "function") {
+      this.statuses.set(
+        name,
+        new Promise((resolve) => {
+          const onload = () => {
+            this.resources.set(name, value);
+            resolve(true);
+            (value as EventSource).removeEventListener("load", onload);
+          };
+          (value as EventSource).addEventListener("load", onload);
+        }),
+      );
+    } else {
+      console.warn("Resource added was not a loadable resource");
+    }
+    this.resources.set(name, value);
+  }
+
+  delete(name: string) {
+    this.resources.delete(name);
+  }
+
+  ready() {
+    return Promise.all(Array.from(this.statuses.values()));
+  }
+}

main.ts

@@ -0,0 +1,54 @@
+import {
+  getContext,
+  setContextItem,
+  setDefaultContext,
+} from "./lib/context.ts";
+import { InputManager } from "./lib/input.ts";
+
+import { Doodler, Vector, ZoomableDoodler } from "@bearmetal/doodler";
+import { ResourceManager } from "./lib/resources.ts";
+import { addButton } from "./ui/button.ts";
+import { TrackSystem } from "./track/system.ts";
+import { StraightTrack } from "./track/shapes.ts";
+import { StateMachine } from "./state/machine.ts";
+import { bootstrapGameStateMachine } from "./state/states/index.ts";
+
+const inputManager = new InputManager();
+const resources = new ResourceManager();
+const doodler = new ZoomableDoodler({
+  fillScreen: true,
+  bg: "#302040",
+});
+// doodler.minScale = 0.1;
+(doodler as any).scale = doodler.maxScale;
+
+setDefaultContext({
+  inputManager,
+  doodler,
+  resources,
+  debug: true,
+  showEnds: true,
+});
+
+const state = bootstrapGameStateMachine();
+setContextItem("state", state);
+
+doodler.init();
+addButton({
+  text: "Hello World!",
+  onClick: () => {
+    console.log("Hello World!");
+  },
+  at: [
+    new Vector(10, doodler.height - 50),
+    new Vector(110, doodler.height - 10),
+  ],
+  style: {
+    fillColor: "blue",
+    color: "white",
+  },
+});
+
+doodler.createLayer((_, __, dTime) => {
+  state.update(dTime);
+});

math/lerp.ts

@@ -1,8 +1,11 @@
-import { Vector } from "doodler";
-
 export const lerp = (a: number, b: number, t: number) => {
-  return (a*t) + (b*(1-t));
+  return (a * t) + (b * (1 - t));
-}
+};
 
-export const map = (value: number, x1: number, y1: number, x2: number, y2: number) => 
+export const map = (
-(value - x1) * (y2 - x2) / (y1 - x1) + x2;
+  value: number,
+  x1: number,
+  y1: number,
+  x2: number,
+  y2: number,
+) => (value - x1) * (y2 - x2) / (y1 - x1) + x2;

math/path.ts

@@ -1,7 +1,6 @@
-import { Vector } from "doodler";
+import { Vector } from "@bearmetal/doodler";
 
 export class ComplexPath {
-
   points: Vector[] = [];
 
   radius = 50;
@@ -22,10 +21,10 @@ export class ComplexPath {
 
     ctx.save();
     ctx.lineWidth = 2;
-    ctx.strokeStyle = 'white';
+    ctx.strokeStyle = "white";
-    ctx.setLineDash([21, 6])
+    ctx.setLineDash([21, 6]);
 
-    let last = this.points[this.points.length - 1]
+    let last = this.points[this.points.length - 1];
 
     for (const point of this.points) {
       ctx.beginPath();
@@ -39,54 +38,34 @@ export class ComplexPath {
 }
 
 export class PathSegment {
-  points: [Vector, Vector, Vector, Vector]
+  points: [Vector, Vector, Vector, Vector];
-  ctx?: CanvasRenderingContext2D;
 
   length: number;
+  startingLength: number;
 
   constructor(points: [Vector, Vector, Vector, Vector]) {
     this.points = points;
     this.length = this.calculateApproxLength(100);
-  }
+    this.startingLength = Math.round(this.length);
-
-  setContext(ctx: CanvasRenderingContext2D) {
-    this.ctx = ctx;
-  }
-
-  draw() {
-    const [a, b, c, d] = this.points;
-    doodler.drawBezier(a, b, c, d, {
-      strokeColor: '#ffffff50'
-    })
-    // if (!this.ctx) return;
-    // const ctx = this.ctx;
-
-    // ctx.save();
-    // ctx.beginPath();
-    // ctx.moveTo(this.points[0].x, this.points[0].y);
-
-    // ctx.bezierCurveTo(
-    //   this.points[1].x,
-    //   this.points[1].y,
-    //   this.points[2].x,
-    //   this.points[2].y,
-    //   this.points[3].x,
-    //   this.points[3].y,
-    // );
-
-    // ctx.strokeStyle = '#ffffff50';
-    // ctx.lineWidth = 2;
-    // ctx.stroke();
-    // ctx.restore();
   }
 
   getPointAtT(t: number) {
     const [a, b, c, d] = this.points;
     const res = a.copy();
 
-    res.add(Vector.add(a.copy().mult(-3), b.copy().mult(3)).mult(t))
+    res.add(Vector.add(a.copy().mult(-3), b.copy().mult(3)).mult(t));
-    res.add(Vector.add(Vector.add(a.copy().mult(3), b.copy().mult(-6)), c.copy().mult(3)).mult(Math.pow(t, 2)));
+    res.add(
-    res.add(Vector.add(Vector.add(a.copy().mult(-1), b.copy().mult(3)), Vector.add(c.copy().mult(-3), d.copy())).mult(Math.pow(t, 3)));
+      Vector.add(
+        Vector.add(a.copy().mult(3), b.copy().mult(-6)),
+        c.copy().mult(3),
+      ).mult(Math.pow(t, 2)),
+    );
+    res.add(
+      Vector.add(
+        Vector.add(a.copy().mult(-1), b.copy().mult(3)),
+        Vector.add(c.copy().mult(-3), d.copy()),
+      ).mult(Math.pow(t, 3)),
+    );
 
     return res;
   }
@@ -123,15 +102,20 @@ export class PathSegment {
         points.push([i * resolution, this]);
       }
     }
-    return points
+    return points;
   }
 
   tangent(t: number) {
-    // dP(t) / dt =  -3(1-t)^2 * P0 + 3(1-t)^2 * P1 - 6t(1-t) * P1 - 3t^2 * P2 + 6t(1-t) * P2 + 3t^2 * P3 
+    // dP(t) / dt =  -3(1-t)^2 * P0 + 3(1-t)^2 * P1 - 6t(1-t) * P1 - 3t^2 * P2 + 6t(1-t) * P2 + 3t^2 * P3
     const [a, b, c, d] = this.points;
 
     const res = Vector.sub(b, a).mult(3 * Math.pow(1 - t, 2));
-    res.add(Vector.add(Vector.sub(c, b).mult(6 * (1 - t) * t), Vector.sub(d, c).mult(3 * Math.pow(t, 2))));
+    res.add(
+      Vector.add(
+        Vector.sub(c, b).mult(6 * (1 - t) * t),
+        Vector.sub(d, c).mult(3 * Math.pow(t, 2)),
+      ),
+    );
 
     return res;
   }
@@ -158,12 +142,12 @@ export class PathSegment {
 
         let dist;
         if (k <= 0.0) {
-          dist = Vector.hypot2(v, a)
+          dist = Vector.hypot2(v, a);
         } else if (k >= 1.0) {
-          dist = Vector.hypot2(v, b)
+          dist = Vector.hypot2(v, b);
         }
 
-        dist = Vector.hypot2(v, d)
+        dist = Vector.hypot2(v, d);
 
         if (dist < distance) {
           distance = dist;
@@ -179,27 +163,32 @@ export class PathSegment {
 
   calculateApproxLength(resolution = 25) {
     const stepSize = 1 / resolution;
-    const points: Vector[] = []
+    const points: Vector[] = [];
     for (let i = 0; i <= resolution; i++) {
       const current = stepSize * i;
-      points.push(this.getPointAtT(current))
+      points.push(this.getPointAtT(current));
     }
-    this.length = points.reduce((acc: { prev?: Vector, length: number }, cur) => {
+    this.length =
-      const prev = acc.prev;
+      points.reduce((acc: { prev?: Vector; length: number }, cur) => {
-      acc.prev = cur;
+        const prev = acc.prev;
-      if (!prev) return acc;
+        acc.prev = cur;
-      acc.length += cur.dist(prev);
+        if (!prev) return acc;
-      return acc;
+        acc.length += cur.dist(prev);
-    }, { prev: undefined, length: 0 }).length
+        return acc;
+      }, { prev: undefined, length: 0 }).length;
     return this.length;
   }
 
-  calculateEvenlySpacedPoints(spacing: number, resolution = 1) {
+  calculateEvenlySpacedPoints(
-    const points: Vector[] = []
+    spacing: number,
+    resolution = 1,
+    targetLength?: number,
+  ) {
+    const points: Vector[] = [];
 
     points.push(this.points[0]);
     let prev = points[0];
-    let distSinceLastEvenPoint = 0
+    let distSinceLastEvenPoint = 0;
 
     let t = 0;
 
@@ -209,10 +198,12 @@ export class PathSegment {
       const point = this.getPointAtT(t);
       distSinceLastEvenPoint += prev.dist(point);
 
-
       if (distSinceLastEvenPoint >= spacing) {
         const overshoot = distSinceLastEvenPoint - spacing;
-        const evenPoint = Vector.add(point, Vector.sub(point, prev).normalize().mult(overshoot))
+        const evenPoint = Vector.add(
+          point,
+          Vector.sub(point, prev).normalize().mult(overshoot),
+        );
         distSinceLastEvenPoint = overshoot;
         points.push(evenPoint);
         prev = evenPoint;
@@ -221,6 +212,46 @@ export class PathSegment {
       prev = point;
     }
 
+    if (targetLength && points.length < targetLength) {
+      while (points.length < targetLength) {
+        t += 1 / div;
+        const point = this.getPointAtT(t);
+        distSinceLastEvenPoint += prev.dist(point);
+
+        if (distSinceLastEvenPoint >= spacing) {
+          const overshoot = distSinceLastEvenPoint - spacing;
+          const evenPoint = Vector.add(
+            point,
+            Vector.sub(point, prev).normalize().mult(overshoot),
+          );
+          distSinceLastEvenPoint = overshoot;
+          points.push(evenPoint);
+          prev = evenPoint;
+        }
+
+        prev = point;
+      }
+    }
+
     return points;
   }
+
+  calculateSubdividedPoints(numberOfPoints: number) {
+    const points: Vector[] = [];
+
+    for (let i = 0; i < numberOfPoints; i++) {
+      const point = this.getPointAtT(i / numberOfPoints);
+      points.push(point);
+    }
+
+    return points;
+  }
+
+  clampLength() {
+    const curveLength = this.startingLength;
+    const points = this.calculateEvenlySpacedPoints(1, 1, curveLength + 1);
+    if (points.length >= curveLength) {
+      this.points[3].set(points[curveLength]);
+    }
+  }
 }

state/machine.ts

@@ -0,0 +1,76 @@
+export class StateMachine<T> {
+  private _states: Map<T, State<T>> = new Map();
+  private currentState?: State<T>;
+
+  update(dt: number, ctx?: CanvasRenderingContext2D) {
+    this.currentState?.update(dt, ctx);
+  }
+
+  get current() {
+    return this.currentState;
+  }
+
+  get states() {
+    return this._states;
+  }
+
+  addState(state: State<T>) {
+    this.states.set(state.name, state);
+  }
+
+  transitionTo(state: T) {
+    if (!this.current) {
+      this.currentState = this._states.get(state)!;
+      this.currentState.start();
+      return;
+    }
+    if (this.current?.canTransitionTo(state) && this._states.has(state)) {
+      this.current.stop();
+      this.currentState = this._states.get(state)!;
+      this.current.start();
+    }
+  }
+}
+
+export abstract class State<T> {
+  protected stateMachine: StateMachine<T>;
+  protected abstract validTransitions: Set<T>;
+
+  abstract readonly name: T;
+
+  constructor(
+    stateMachine: StateMachine<T>,
+  ) {
+    this.stateMachine = stateMachine;
+  }
+
+  abstract update(dt: number, ctx?: CanvasRenderingContext2D): void;
+  abstract start(): void;
+  abstract stop(): void;
+
+  canTransitionTo(state: T) {
+    return this.validTransitions.has(state);
+  }
+}
+
+export abstract class ExtensibleState<T> extends State<T> {
+  extensions: Map<string, (...args: unknown[]) => void> = new Map();
+  registerExtension(name: string, cb: (...args: unknown[]) => void) {
+    this.extensions.set(name, cb);
+  }
+
+  constructor(stateMachine: StateMachine<T>) {
+    super(stateMachine);
+    const oldUpdate = this.update;
+    this.update = function (dt: number, ctx?: CanvasRenderingContext2D) {
+      oldUpdate.apply(this, [dt, ctx]);
+      this.runExtensions(dt, ctx);
+    };
+  }
+
+  runExtensions(...args: unknown[]) {
+    for (const [name, cb] of this.extensions) {
+      cb(...args);
+    }
+  }
+}

state/states/EditTrackState.ts

@@ -0,0 +1,165 @@
+import { Doodler, Vector } from "@bearmetal/doodler";
+import { getContextItem, setContextItem } from "../../lib/context.ts";
+import { InputManager } from "../../lib/input.ts";
+import { TrackSystem } from "../../track/system.ts";
+import { State, StateMachine } from "../machine.ts";
+import { States } from "./index.ts";
+import { StraightTrack } from "../../track/shapes.ts";
+import { TrackSegment } from "../../track/system.ts";
+
+export class EditTrackState extends State<States> {
+  override name: States = States.EDIT_TRACK;
+  override validTransitions: Set<States> = new Set([
+    States.RUNNING,
+    States.PAUSED,
+  ]);
+
+  private heldEvents: Map<string | number, (() => void) | undefined> =
+    new Map();
+
+  private currentSegment?: TrackSegment;
+
+  override update(dt: number): void {
+    const inputManager = getContextItem<InputManager>("inputManager");
+    const track = getContextItem<TrackSystem>("track");
+
+    // For moving a segment, i.e. the currently active one
+    // const segment = track.lastSegment;
+    // if (segment) {
+    //   const firstPoint = segment.points[0].copy();
+    //   const { x, y } = inputManager.getMouseLocation();
+    //   segment.points.forEach((p, i) => {
+    //     const relativePoint = Vector.sub(p, firstPoint);
+    //     p.set(x, y);
+    //     p.add(relativePoint);
+    //   });
+    // }
+
+    // manipulate only end of segment while maintaining length
+    // const segment = track.lastSegment;
+    // if (segment) {
+    //   const p3 = segment.points[2];
+    //   const p4 = segment.points[3];
+    //   let curveLength = Math.round(segment.calculateApproxLength());
+    //   this.startingLength = this.startingLength ?? curveLength;
+    //   curveLength = this.startingLength;
+    //   const { x, y } = inputManager.getMouseLocation();
+    //   p4.set(x, y);
+    //   const points = segment.calculateEvenlySpacedPoints(1);
+    //   if (points.length > curveLength) p4.set(points[curveLength - 1]);
+
+    //   // doodler.fillText(curveLength.toFixed(2), p3.copy().add(10, 0), 100);
+    // }
+    const doodler = getContextItem<Doodler>("doodler");
+
+    // Adjust angles until tangent points to mouse
+    const segment = this.currentSegment;
+    if (segment) {
+      segment.propagate();
+
+      const mousePos = inputManager.getMouseLocationV();
+      const p1 = segment.points[0];
+      const p2 = segment.points[1];
+      const p3 = segment.points[2];
+      const p4 = segment.points[3];
+
+      const prevp3 = p3.copy();
+      const dirToMouse = Vector.sub(mousePos, p2).normalize();
+      const angleToMouse = dirToMouse.heading();
+      const angleToP1 = Vector.sub(p2, p1).heading();
+      const p2DistToMouse = Vector.dist(p2, mousePos);
+      const p3DistToMouse = Vector.dist(p3, mousePos);
+      const distToP3 = Vector.dist(p2, p3);
+      const distToP4 = Vector.dist(prevp3, p4);
+      if (
+        Math.abs(angleToMouse - angleToP1) < .6 &&
+        p2DistToMouse > distToP3 &&
+        p3DistToMouse > distToP4
+      ) {
+        {
+          const dirToNewP3 = dirToMouse.copy().rotate(
+            -(angleToMouse - angleToP1) / 2,
+          );
+          dirToNewP3.setMag(distToP3);
+          p3.set(Vector.add(p2, dirToNewP3));
+          doodler.line(p2, Vector.add(p2, dirToNewP3), { color: "blue" });
+          doodler.line(p2, Vector.add(p2, dirToMouse.mult(100)), {
+            color: "red",
+          });
+        }
+        {
+          const dirToMouse = Vector.sub(mousePos, p3).normalize();
+          dirToMouse.setMag(distToP4);
+          p4.set(Vector.add(p3, dirToMouse));
+          doodler.line(p3, Vector.add(p3, dirToMouse), { color: "green" });
+        }
+        segment.clampLength();
+      }
+      doodler.fillText(
+        segment.calculateApproxLength().toFixed(2),
+        p2.copy().add(10, 0),
+        100,
+      );
+    }
+
+    track.draw(true);
+    // TODO
+    // Draw ui
+    // Draw track points
+    // Draw track tangents
+  }
+  override start(): void {
+    const inputManager = getContextItem<InputManager>("inputManager");
+    this.heldEvents.set("e", inputManager.offKey("e"));
+    this.heldEvents.set("Escape", inputManager.offKey("Escape"));
+    inputManager.onKey("e", () => {
+      const state = getContextItem<StateMachine<States>>("state");
+      state.transitionTo(States.RUNNING);
+    });
+
+    const track = getContextItem<TrackSystem>("track");
+    setContextItem("trackCopy", track.copy());
+    inputManager.onKey("Escape", () => {
+      const trackCopy = getContextItem<TrackSystem>("trackCopy");
+      setContextItem("track", trackCopy);
+      setContextItem("trackCopy", undefined);
+      const state = getContextItem<StateMachine<States>>("state");
+      state.transitionTo(States.RUNNING);
+    });
+
+    inputManager.onKey("w", () => {
+      const track = getContextItem<TrackSystem>("track");
+      const segment = track.lastSegment;
+      if (!segment) return;
+      const n = new StraightTrack(segment.points[3]);
+      const t = segment.tangent(1).heading();
+      n.rotate(t);
+      segment.frontNeighbours.push(n);
+      track.registerSegment(n);
+      this.currentSegment = n;
+    });
+
+    inputManager.onKey("1", () => {
+      this.currentSegment = track.firstSegment;
+    });
+
+    this.currentSegment = track.lastSegment;
+
+    // TODO
+    // Cache trains and save
+  }
+  override stop(): void {
+    const inputManager = getContextItem<InputManager>("inputManager");
+    inputManager.offKey("e");
+    inputManager.offKey("Escape");
+    if (this.heldEvents.size > 0) {
+      for (const [key, cb] of this.heldEvents) {
+        if (cb) {
+          getContextItem<InputManager>("inputManager").onKey(key, cb);
+        }
+        this.heldEvents.delete(key);
+      }
+    }
+    setContextItem("trackCopy", undefined);
+  }
+}

state/states/EditTrainState.ts

@@ -0,0 +1,25 @@
+import { State } from "../machine.ts";
+import { States } from "./index.ts";
+
+export class EditTrainState extends State<States> {
+  override name: States = States.EDIT_TRAIN;
+  override validTransitions: Set<States> = new Set([
+    States.RUNNING,
+    States.PAUSED,
+  ]);
+
+  override update(dt: number): void {
+    throw new Error("Method not implemented.");
+  }
+  override start(): void {
+    throw new Error("Method not implemented.");
+    // TODO
+    // Cache trains
+    // Stash train in context
+    // Draw track
+    // Draw train (filtered by train ID)
+  }
+  override stop(): void {
+    throw new Error("Method not implemented.");
+  }
+}

state/states/LoadState.ts

@@ -0,0 +1,51 @@
+import { bootstrapInputs } from "../../inputs.ts";
+import { setContextItem } from "../../lib/context.ts";
+import { InputManager } from "../../lib/input.ts";
+import { ResourceManager } from "../../lib/resources.ts";
+import { StraightTrack } from "../../track/shapes.ts";
+import { TrackSystem } from "../../track/system.ts";
+import { State } from "../machine.ts";
+import { States } from "./index.ts";
+
+export class LoadState extends State<States> {
+  override name: States = States.LOAD;
+  override validTransitions: Set<States> = new Set([
+    States.RUNNING,
+  ]);
+
+  override update(): void {
+    // noop
+  }
+  override start(): void {
+    const track = this.loadTrack() ?? new TrackSystem([new StraightTrack()]);
+    setContextItem("track", track);
+
+    const trains = this.loadTrains() ?? [];
+    setContextItem("trains", trains);
+
+    const resources = new ResourceManager();
+    setContextItem("resources", resources);
+
+    const inputManager = new InputManager();
+    setContextItem("inputManager", inputManager);
+
+    bootstrapInputs();
+
+    this.stateMachine.transitionTo(States.RUNNING);
+  }
+  override stop(): void {
+    // noop
+  }
+
+  private loadTrack() {
+    const track = TrackSystem.deserialize(
+      JSON.parse(localStorage.getItem("track") || "[]"),
+    );
+    return track;
+  }
+
+  private loadTrains() {
+    const trains = JSON.parse(localStorage.getItem("trains") || "[]");
+    return trains;
+  }
+}

state/states/PausedState.ts

@@ -0,0 +1,30 @@
+import { State } from "../machine.ts";
+import { States } from "./index.ts";
+
+export class PausedState extends State<States> {
+  override name: States = States.PAUSED;
+  override validTransitions: Set<States> = new Set([
+    States.LOAD,
+    States.RUNNING,
+    States.EDIT_TRACK,
+    States.EDIT_TRAIN,
+  ]);
+  override update(dt: number): void {
+    throw new Error("Method not implemented.");
+    // TODO
+    // Handle input
+    // Draw ui
+  }
+  override start(): void {
+    throw new Error("Method not implemented.");
+    // TODO
+    // Save tracks to cache
+    // Save trains to cache
+    // Save resources to cache
+  }
+  override stop(): void {
+    throw new Error("Method not implemented.");
+    // TODO
+    // Do nothing
+  }
+}

state/states/RunningState.ts

@@ -0,0 +1,32 @@
+import { getContext } from "../../lib/context.ts";
+import { TrackSystem } from "../../track/system.ts";
+import { Train } from "../../train/train.ts";
+import { State } from "../machine.ts";
+import { States } from "./index.ts";
+
+export class RunningState extends State<States> {
+  override name: States = States.RUNNING;
+  override validTransitions: Set<States> = new Set([
+    States.PAUSED,
+    States.EDIT_TRACK,
+  ]);
+  override update(dt: number): void {
+    const ctx = getContext() as { trains: Train[]; track: TrackSystem };
+    // TODO
+    // Update trains
+    // Update world
+    // Handle input
+    // Draw (maybe via a layer system that syncs with doodler)
+    ctx.track.draw();
+    for (const train of ctx.trains) {
+      train.draw();
+    }
+    // Monitor world events
+  }
+  override start(): void {
+    // noop
+  }
+  override stop(): void {
+    // noop
+  }
+}

state/states/index.ts

@@ -0,0 +1,26 @@
+import { StateMachine } from "../machine.ts";
+import { Track } from "../../track.ts";
+import { EditTrainState } from "./EditTrainState.ts";
+import { EditTrackState } from "./EditTrackState.ts";
+import { PausedState } from "./PausedState.ts";
+import { RunningState } from "./RunningState.ts";
+import { LoadState } from "./LoadState.ts";
+
+export enum States {
+  LOAD,
+  RUNNING,
+  PAUSED,
+  EDIT_TRACK,
+  EDIT_TRAIN,
+}
+
+export function bootstrapGameStateMachine() {
+  const stateMachine = new StateMachine<States>();
+  stateMachine.addState(new LoadState(stateMachine));
+  stateMachine.addState(new RunningState(stateMachine));
+  stateMachine.addState(new PausedState(stateMachine));
+  stateMachine.addState(new EditTrackState(stateMachine));
+  stateMachine.addState(new EditTrainState(stateMachine));
+  stateMachine.transitionTo(States.LOAD);
+  return stateMachine;
+}

test/bench.ts

@@ -0,0 +1,38 @@
+import { assert } from "jsr:@std/assert";
+import { describe, it } from "jsr:@std/testing/bdd";
+
+/**
+ * Tests if a function can run a given number of iterations within a target frame time.
+ * @param fn The function to test.
+ * @param iterations Number of times to run the function per frame.
+ * @param fps Target frames per second.
+ */
+export function testPerformance(
+  fn: () => unknown,
+  iterations: number,
+  fps: number,
+) {
+  console.log(`Performance Test - ${iterations} iterations at ${fps} FPS`);
+  const frameTime = 1000 / fps;
+  const startTime = performance.now();
+
+  for (let i = 0; i < iterations; i++) {
+    fn();
+  }
+
+  const endTime = performance.now();
+  const elapsed = endTime - startTime;
+
+  console.log(
+    `Elapsed time: ${elapsed.toFixed(2)}ms (Target: ≤${
+      frameTime.toFixed(2)
+    }ms)`,
+  );
+  assert(
+    elapsed <= frameTime,
+    `Function took too long: ${elapsed.toFixed(2)}ms (Target: ≤${
+      frameTime.toFixed(2)
+    }ms)`,
+  );
+  // });
+}

test/contextBench.test.js

@@ -0,0 +1,49 @@
+import {
+  getContextItem,
+  setContextItem,
+  setDefaultContext,
+  withContext,
+} from "../lib/context.ts"; // adjust path as needed
+import { testPerformance } from "./bench.ts";
+
+/**
+ * Benchmarks the performance of setting and getting context items.
+ * All context transactions should run 10000 times within the 60 FPS frame time.
+ * getContextItem should run 100000 times within the 240 FPS frame time to ensure adequate performance.
+ */
+Deno.test("Context Benchmark", () => {
+  console.log("Context Benchmark - run within frame time");
+  testPerformance(
+    () => {
+      setDefaultContext({ a: 1 });
+    },
+    10000,
+    60,
+  );
+
+  testPerformance(
+    () => {
+      withContext({ a: 1 }, () => {
+        getContextItem("a");
+      });
+    },
+    10000,
+    60,
+  );
+
+  testPerformance(
+    () => {
+      getContextItem("a");
+    },
+    100000,
+    240,
+  );
+
+  testPerformance(
+    () => {
+      setContextItem("a", 1);
+    },
+    10000,
+    60,
+  );
+});

track/shapes.ts

@@ -0,0 +1,14 @@
+import { Vector } from "@bearmetal/doodler";
+import { TrackSegment } from "./system.ts";
+
+export class StraightTrack extends TrackSegment {
+  constructor(start?: Vector) {
+    start = start || new Vector(100, 100);
+    super([
+      start,
+      start.copy().add(25, 0),
+      start.copy().add(75, 0),
+      start.copy().add(100, 0),
+    ]);
+  }
+}

track/system.ts

@@ -0,0 +1,234 @@
+import { Doodler, Vector } from "@bearmetal/doodler";
+import { PathSegment } from "../math/path.ts";
+import { getContextItem, setDefaultContext } from "../lib/context.ts";
+
+export class TrackSystem {
+  private segments: Map<string, TrackSegment> = new Map();
+  private doodler: Doodler;
+
+  constructor(segments: TrackSegment[]) {
+    this.doodler = getContextItem<Doodler>("doodler");
+    for (const segment of segments) {
+      this.segments.set(segment.id, segment);
+    }
+  }
+
+  get firstSegment() {
+    return this.segments.values().next().value;
+  }
+
+  get lastSegment() {
+    return this.segments.values().toArray().pop();
+  }
+
+  registerSegment(segment: TrackSegment) {
+    segment.setTrack(this);
+    this.segments.set(segment.id, segment);
+  }
+
+  draw(showControls = false) {
+    for (const segment of this.segments.values()) {
+      segment.draw(showControls);
+    }
+
+    try {
+      if (getContextItem<boolean>("showEnds")) {
+        const ends = this.findEnds();
+        for (const end of ends) {
+          this.doodler.fillCircle(end.pos, 2, {
+            color: "red",
+            // weight: 3,
+          });
+          if (getContextItem<boolean>("debug")) {
+            this.doodler.line(
+              end.pos,
+              end.pos.copy().add(end.tangent.copy().mult(20)),
+              {
+                color: "blue",
+                // weight: 3,
+              },
+            );
+          }
+        }
+      }
+    } catch {
+      setDefaultContext({ showEnds: false });
+    }
+  }
+
+  findEnds() {
+    const ends: { pos: Vector; segment: TrackSegment; tangent: Vector }[] = [];
+    for (const segment of this.segments.values()) {
+      const [a, b, c, d] = segment.points;
+      {
+        const tangent = Vector.sub(a, b).normalize();
+        const pos = a.copy();
+        ends.push({ pos, segment, tangent });
+      }
+      {
+        const tangent = Vector.sub(d, c).normalize();
+        const pos = d.copy();
+        ends.push({ pos, segment, tangent });
+      }
+    }
+    return ends;
+  }
+
+  serialize() {
+    return this.segments.values().map((s) => s.serialize()).toArray();
+  }
+
+  copy() {
+    const track = new TrackSystem([]);
+    for (const segment of this.segments.values()) {
+      track.segments.set(segment.id, segment.copy());
+    }
+    return track;
+  }
+
+  static deserialize(data: any) {
+    if (data.length === 0) return undefined;
+    const track = new TrackSystem([]);
+    const neighborMap = new Map<string, [string[], string[]]>();
+    for (const segment of data) {
+      track.segments.set(segment.id, TrackSegment.deserialize(segment));
+    }
+    for (const segment of track.segments.values()) {
+      segment.setTrack(track);
+      const neighbors = neighborMap.get(segment.id);
+      if (neighbors) {
+        segment.backNeighbours = neighbors[1].map((id) =>
+          track.segments.get(id)
+        ).filter((s) => s) as TrackSegment[];
+        segment.frontNeighbours = neighbors[0].map((id) =>
+          track.segments.get(id)
+        ).filter((s) => s) as TrackSegment[];
+      }
+    }
+    return track;
+  }
+}
+
+type VectorSet = [Vector, Vector, Vector, Vector];
+
+export class TrackSegment extends PathSegment {
+  frontNeighbours: TrackSegment[] = [];
+  backNeighbours: TrackSegment[] = [];
+
+  track?: TrackSystem;
+
+  doodler: Doodler;
+
+  id: string;
+
+  constructor(p: VectorSet, id?: string) {
+    super(p);
+    this.doodler = getContextItem<Doodler>("doodler");
+    this.id = id ?? crypto.randomUUID();
+  }
+
+  setTrack(t: TrackSystem) {
+    this.track = t;
+  }
+
+  draw(showControls = false) {
+    this.doodler.drawBezier(
+      this.points[0],
+      this.points[1],
+      this.points[2],
+      this.points[3],
+      {
+        strokeColor: "#ffffff50",
+      },
+    );
+    if (showControls) {
+      // this.doodler.drawCircle(this.points[0], 4, {
+      //   color: "red",
+      //   weight: 3,
+      // });
+      this.doodler.drawCircle(this.points[1], 4, {
+        color: "red",
+        weight: 3,
+      });
+      this.doodler.drawCircle(this.points[2], 4, {
+        color: "red",
+        weight: 3,
+      });
+      // this.doodler.drawCircle(this.points[3], 4, {
+      //   color: "red",
+      //   weight: 3,
+      // });
+    }
+  }
+
+  serialize() {
+    return {
+      p: this.points.map((p) => p.array()),
+      id: this.id,
+      bNeighbors: this.backNeighbours.map((n) => n.id),
+      fNeighbors: this.frontNeighbours.map((n) => n.id),
+    };
+  }
+
+  copy() {
+    return new TrackSegment(
+      this.points.map((p) => p.copy()) as VectorSet,
+      this.id,
+    );
+  }
+
+  propagate() {
+    const [_, __, p3, p4] = this.points;
+    const tangent = Vector.sub(p4, p3);
+    for (const fNeighbour of this.frontNeighbours) {
+      fNeighbour.receivePropagation(tangent);
+    }
+  }
+
+  lastHeading?: number;
+
+  receivePropagation(tangent: Vector) {
+    const [p1, p2, p3, p4] = this.points;
+    // const angle = tangent.heading() - (this.lastHeading ?? 0);
+    // this.lastHeading = tangent.heading();
+    // const newP2 = Vector.add(p1, tangent);
+    // const p2ToP3 = Vector.sub(p3, p2);
+    // p2ToP3.rotate(angle);
+    // p3.set(Vector.add(newP2, p2ToP3));
+    // const p2Top4 = Vector.sub(p4, p2);
+    // p2Top4.rotate(angle);
+    // p4.set(Vector.add(newP2, p2Top4));
+    // p2.set(newP2);
+    this.rotate(tangent);
+    this.propagate();
+  }
+
+  // TODO: this duplicates receivePropagation, but for some reason it doesn't work when called from receivePropagation
+  rotate(angle: number | Vector) {
+    const [p1, p2, p3, p4] = this.points;
+    let newP2;
+    if (angle instanceof Vector) {
+      const tan = angle;
+      angle = tan.heading() - (this.lastHeading ?? 0);
+      this.lastHeading = tan.heading();
+      newP2 = Vector.add(p1, tan);
+    } else {
+      const p1ToP2 = Vector.sub(p2, p1);
+      p1ToP2.rotate(angle);
+      newP2 = Vector.add(p1, p1ToP2);
+    }
+    const p2ToP3 = Vector.sub(p3, p2);
+    p2ToP3.rotate(angle);
+    p3.set(Vector.add(newP2, p2ToP3));
+    const p2Top4 = Vector.sub(p4, p2);
+    p2Top4.rotate(angle);
+    p4.set(Vector.add(newP2, p2Top4));
+    p2.set(newP2);
+  }
+  static deserialize(data: any) {
+    return new TrackSegment(
+      data.p.map((p: [number, number, number]) => new Vector(p[0], p[1], p[2])),
+      data.id,
+    );
+  }
+}

train/train.ts

@@ -1,9 +1,9 @@
-import { drawLine } from "../drawing/line.ts";
 import { ComplexPath, PathSegment } from "../math/path.ts";
-import { Vector } from "doodler";
 import { Follower } from "../physics/follower.ts";
 import { Mover } from "../physics/mover.ts";
 import { Spline, Track } from "../track.ts";
+import { getContextItem } from "../lib/context.ts";
+import { Doodler, Vector } from "@bearmetal/doodler";
 
 export class Train {
   nodes: Vector[] = [];
@@ -83,6 +83,12 @@ export class Train {
   //   }
   // }
 
+  draw() {
+    for (const car of this.cars) {
+      car.draw();
+    }
+  }
+
   real2Track(length: number) {
     return length / this.path.pointSpacing;
   }
@@ -113,6 +119,7 @@ export class TrainCar {
 
   draw() {
     if (!this.points) return;
+    const doodler = getContextItem<Doodler>("doodler");
     const [a, b] = this.points;
     const origin = Vector.add(Vector.sub(a, b).div(2), b);
     const angle = Vector.sub(b, a).heading();

ui/button.ts

@@ -0,0 +1,39 @@
+import { Doodler, Vector } from "@bearmetal/doodler";
+import { getContext, getContextItem } from "../lib/context.ts";
+
+export function addButton(props: {
+  text: string;
+  onClick: () => void;
+  style?: {
+    color?: string;
+    fillColor?: string;
+    strokeColor?: string;
+    weight?: number;
+    noStroke?: boolean;
+    noFill?: boolean;
+  };
+  at: [Vector, Vector];
+}) {
+  const doodler = getContextItem<Doodler>("doodler");
+  const { text, onClick, style } = props;
+  const { x, y } = props.at[1].copy().sub(props.at[0]);
+  const id = doodler.addUIElement(
+    "rectangle",
+    props.at[0],
+    x,
+    y,
+    style,
+  );
+  doodler.registerClickable(props.at[0], props.at[1], onClick);
+  return {
+    id,
+    text,
+    onClick,
+    style,
+  };
+}
+
+export function removeButton(id: string, onClick: () => void) {
+  getContextItem<Doodler>("doodler").removeUIElement(id);
+  getContextItem<Doodler>("doodler").unregisterClickable(onClick);
+}